The meaning of "color" is explained in the lectures of Buddhist masters and the discussions of folk knowledge celebrities. What we saw at first was different, but later we all reached a consensus that colors are all material phenomena. "Empty", few people dare to say that it has nothing, although "empty" also has this meaning. So there are definitions of "self-emptiness", "non-emptiness" and "emptiness without emptiness". Of course, there are also very few people who hold the extreme view of "extinction" and think that there is nothing. No matter how good the predecessors said, as an afterlife, I dare not copy and imitate; If you want to say it, just say your own understanding.
Color refers to all phenomena that our eyes can see, including fine substances observed under high-power electron microscope, and even "atoms in atoms". Color can be explained in this way, but the color in Heart Sutra is not used to explain material phenomena other than ourselves, but specifically refers to our bodies. Because the premise of Buddhism explaining the truth of "color emptiness" is based on breaking the persistence of "man and me"; And after the color, four psychological reactions of "thinking and knowing" are listed. Obviously, the purpose of expounding the truth of "color emptiness" is to analyze and decide whether the five-implication human phase of material and spiritual synthesis is true or not. So I think the color in the Heart Sutra refers to our "color body".
"Empty" and "empty" mean that there is no entity, only appearance. Although it is synonymous with "nothing", it does not mean that there is absolutely nothing. The use of "emptiness" here is to explain to people that the noumenon of "color" is only a representation-virtual image-illusion, and there is no real reality. This new knowledge that subverts our traditional understanding is hard to be accepted by people. If you want to accept this new knowledge, you must learn the origin theory of Buddhism. This was difficult to do in ancient times when science and technology were backward. Fortunately, with the development of science and technology, we have physics. We can refer to the quantum theory of physics, substance-molecule-atom-proton-particle and other related explanations to understand the origin theory well.
If you don't use the predicate "undifferentiated" in the middle of "color space", you can't understand the true meaning of this sentence. "No difference" means the same equality, and there is no difference. The word "undifferentiated" is used here to show that "color and emptiness" are the same thing.
At this point, we should have a clear understanding of "color is empty". The sentence "color is the same" tells us that our persistent self-righteous body is not real or false, but an illusion, a virtual image synthesized by various causal conditions; This is not the real me.
Understand that "color is not different from empty", then "empty is not different from color" does not need to be repeated; Because "space is the same color" is an inverted sentence of "space is the same color", saying more can only repeat the above meaning. As for "that is" in the last two sentences, it means "that is", which shows more clearly that our bodies are empty images and illusions than the tone of "no difference" ...
If we can wake up and understand that physical phenomena and mental reactions are not the true self, we can know the true self, stop thinking about clinging to everything, achieve complete consciousness and get rid of it. This is exactly what the Prajna Heart Sutra states: "There is no difference between color and emptiness ...".
This is my understanding of "color is empty … color is empty …".